JP4526987B2 - Manufacturing method of polishing buff material - Google Patents

Description

  The present invention relates to a method for producing a polishing buff material for removing a flash by polishing an outer peripheral edge of a silicon wafer used as a semiconductor, for example.

  In this type of silicon wafer, it is necessary to clarify the direction of the crystal axis for processing. In order to indicate the direction of the crystal axis, an orientation flat (a so-called orientation flat) is formed by notching a part of the disk-shaped silicon wafer in the direction of the crystal axis, or only a part of the periphery of the silicon wafer is notched. A step of forming the notch is provided. On the other hand, in recent years, wafers have become larger, and wafers having a diameter of 8 inches have also appeared. In such a large-diameter wafer, if an orientation flat is provided, a wasteful portion to be discarded increases. Therefore, an orientation flat is not provided and a notch portion tends to be provided.

Moreover, in order to remove the flash formed on the outer peripheral edge of the wafer, a conventional nonwoven fabric has been used. That is, a polishing slurry in which fine powder of cerium oxide is dispersed in water is impregnated into a non-woven fabric, and the outer peripheral edge of the wafer is polished using the slurry. However, although the nonwoven fabric is excellent in water absorption, fibers may fray during polishing to remove burrs, which may damage the wafer. And since the whole nonwoven fabric absorbs water, when it presses toward a grinding | polishing target object, it drains from other than a press part and polishing efficiency falls. Therefore, a material using hard foamed urethane as a polishing buff material has been proposed (see, for example, Patent Document 1). This polishing buff material is formed in a cylindrical shape with a projecting peripheral portion provided on the inner peripheral surface, the notch portion of the wafer is directed toward the projecting peripheral portion, the projecting peripheral portion is advanced into the notch portion, and contacted, The inner end face of the notch portion is polished by rotating the polishing buff material.
JP-A-7-68461 (Pages 2 and 5)

  By the way, since hard foam urethane generally has a closed cell structure, its water absorption is low, and its water absorption is uniform throughout. For this reason, when hard foamed urethane is used as a polishing buff material, the water absorption of the polishing slurry is poor, the outer peripheral edge of the wafer cannot be sufficiently polished, and the water absorption is uniform throughout. Therefore, there is a problem that water absorption and water discharge cannot be performed effectively and polishing efficiency is poor.

  Accordingly, an object of the present invention is to provide a method for producing a polishing buff material capable of sufficiently and efficiently polishing an object to be polished.

In order to achieve the above object, a method for producing a polishing buff according to claim 1 is a polyurethane comprising a polyol, a polyisocyanate, a foaming agent, a catalyst and polyethylene glycol or a derivative thereof comprising a polyester polyol. A polyurethane foam obtained by reacting a foam raw material, foaming and curing is heated and pressed, and a film is formed on the pressed surface.

  The method for producing a polishing buff material according to claim 2 is the invention according to claim 1, wherein the blending amount of the polyethylene glycol or a derivative thereof is 0.5 to 10 parts by mass per 100 parts by mass of polyols. It is characterized by being.

  The method for producing a polishing buff material according to a third aspect of the present invention is the invention according to the first or second aspect, wherein the polyurethane foam has a cell number defined in JIS K6400 of 40 to 100 / It is characterized by being 25 mm.

  A method for producing a polishing buff material according to a fourth aspect of the invention is the invention according to any one of the first to third aspects, wherein the compression ratio by the heating press is 5 to 10 times. It is what.

According to the present invention, the following effects can be exhibited.
In the method for producing a polishing buff material according to the first aspect of the invention, a polyurethane foam obtained by reacting, foaming and curing a polyurethane foam material containing polyethylene glycol or a derivative thereof is heated and pressed, This is done by forming a film on the pressed surface. Since the polyurethane foam material contains polyethylene glycol or its derivatives, hydrophilicity is imparted to the polyurethane foam, and the polyurethane foam is heated and pressed, so capillarity occurs in the cells of the polyurethane foam. Absorbs water. By using such a polyurethane foam as a polishing buff material, water in the polishing slurry is absorbed or released into the polyurethane foam, and sufficient polishing can be performed on the object to be polished. Furthermore, a film is formed on the press surface of the polyurethane foam, and since the film is non-water-absorbing, water absorption and water discharge during polishing can be limited to a portion facing the object to be polished. Can be performed efficiently.

  In the method for producing a polishing buff material according to claim 2, polyethylene glycol or a derivative thereof is blended in the polyurethane foam raw material in an amount of 0.5 to 10 parts by mass per 100 parts by mass of the polyol. The effect of the invention according to claim 1 can be sufficiently exhibited.

  In the method for producing a polishing buff material according to claim 3, the number of cells defined in JIS K6400 of polyurethane foam is set to 40 to 100 cells / 25 mm, and sufficient water absorption can be obtained. Therefore, the effect of the invention according to claim 1 or claim 2 can be improved.

  In the manufacturing method of the polishing buff material of the invention according to claim 4, since the compression ratio by the hot press is 5 to 10, the effect of the invention according to any one of claims 1 to 3 is achieved. In addition, the water absorption of the polyurethane foam can be improved, and the non-water absorption of the film can be improved.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1A is an explanatory view schematically showing a molded body 12 made of a polyurethane foam having cells 11 having an open cell structure and imparted with hydrophilicity. The polyurethane foam has an open-cell structure and can exhibit resilience to a compressive load, that is, a soft foam. The cell 11 has a long oval shape in the thickness direction of the molded body 12 and is present in a uniform size.

  In FIG. 1B, a molded body 12 made of polyurethane foam is hot-pressed, and a high-density film 14 is formed on the pressed surface (near the surface) 13. It is explanatory drawing which shows the formed press molded object 16 typically. The molded body 12 is compressed about 3 to 10 times by a heating press, the press surface 13 side is easily compressed by heating, and becomes a coating 14 of a high-density layer, and the intermediate portion 15 has a lower density than the coating 14 depending on the compression ratio. It is a density layer. Therefore, the high-density coating 14 exhibits non-water absorption and the low-density intermediate portion 15 exhibits water absorption. The cells 11 of the press-formed body 16 have an oval shape that is longer in the plate surface direction, and the cells 11 of the coating 14 are formed flatter than the cells 11 of the intermediate portion 15.

  As shown in FIGS. 2A and 2B, a silicon wafer 17 to be polished used as a semiconductor has a disk shape, and a notch portion 18 that is notched in an inverted V shape is provided in a part thereof. It has been. A polishing buff material 19 is used to remove the outer peripheral edge of the silicon wafer 17 and the flash of the notch portion 18. The press-molded body 16 is used as the polishing buff material 19. The polishing buff material 19 is formed in a disk shape by a press-molded body 16 having a coating 14 on both surfaces of the intermediate portion 15 as described above. A bulging portion 20 having an arcuate cross section is provided on the outer peripheral surface of the polishing buff material 19, and polishing can be performed by the bulging portion 20. A holding jig 21 for holding the polishing buff material 19 is provided on both surfaces of the polishing buff material 19 so that the silicon wafer 17 can be polished by rotating the polishing buff material 19. . A discharge portion 22 for the polishing slurry 23 is disposed above the polishing buff material 19 and is configured to perform polishing while discharging the polishing slurry 23.

  Since the polyurethane foam is hydrophilized with a compound imparting hydrophilicity and is compressed as described above, water is absorbed into the cells 11 of the polyurethane foam having an open cell structure by capillary action. It is thought that it will become. Therefore, water is sufficiently absorbed and discharged at the intermediate portion 15 of the polyurethane foam, and the film 14 is non-water-absorbing because the foam has a high density, and water absorption and discharge are restricted. When this press-formed body 16 is used as the polishing buff material 19, the intermediate portion 15 of the press-formed body 16 is arranged so as to contact the object to be polished, so that the intermediate portion 15 becomes the polishing slurry 23. While absorbing and releasing the water therein, the coating 14 functions to regulate the entry and exit of the water.

  A porous polyurethane foam having cells 11 having an open cell structure is obtained by reacting, foaming and curing raw materials of a polyurethane foam containing polyols, polyisocyanates, a foaming agent and a catalyst. In this case, it is preferable that 0.5 to 10 parts by mass of polyethylene glycol or a derivative thereof for imparting hydrophilicity is added to the polyurethane foam raw material per 100 parts by mass of polyols. When this compounding quantity is less than 0.5 mass part, sufficient hydrophilicity cannot be provided to a polyurethane foam, and it becomes difficult to obtain water absorption. On the other hand, when the amount exceeds 10 parts by mass, excessive polyurethane is imparted to the polyurethane foam, which is not preferable because moldability is deteriorated.

  As the polyols, polyester polyols or polyether polyols are used. As polyester polyols, in addition to condensation polyester polyols obtained by reacting polycarboxylic acids such as adipic acid and phthalic acid with polyols such as ethylene glycol, diethylene glycol, propylene glycol and glycerin, lactone polyester polyols and polycarbonate systems A polyol is mentioned. Examples of the polyether polyol include polypropylene glycol, polytetramethylene glycol, modified products thereof, and compounds obtained by adding alkylene oxide to glycerin. These polyols can change the number of hydroxyl groups and the hydroxyl value by adjusting the kind of raw material components, the molecular weight, the degree of condensation, and the like.

  As the polyols, since the polyester polyol does not exhibit compatibility with polyethylene glycol or its derivative, a unit based on polyethylene glycol or its derivative can appear on the surface in the polyurethane foam, and hydrophilicity can be effectively expressed. preferable.

  The hydroxyl value of the polyols is preferably less than 250 (mgKOH / g), more preferably 50 to 70 (mgKOH / g). By using polyols having such a hydroxyl value, it is possible to obtain a polyurethane foam that is excellent in reactivity with polyisocyanates and is appropriately crosslinked. When the hydroxyl value of polyols is 250 (mgKOH / g) or more, the crosslinking density becomes too high, the foam becomes hard, and the water absorption is also lowered. On the other hand, when the hydroxyl value is less than 50 (mgKOH / g), the hydroxyl value becomes too small, and the crosslinking density of the polyurethane foam tends to be low, and the strength of the foam tends to decrease.

  Next, polyisocyanates to be reacted with polyols are compounds having a plurality of isocyanate groups, specifically, tolylene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate ( NDI), triphenylmethane triisocyanate, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI) and the like are used.

  Here, the isocyanate index of the polyisocyanates is preferably 100 to 120. In other words, the isocyanate index is a percentage of the equivalent ratio of the isocyanate group of the polyisocyanate to the hydroxyl group of the polyol and the blowing agent (water), but the value exceeds 100 means that the isocyanate group is more than the hydroxyl group. Means excess. When the isocyanate index is less than 100, the reaction of polyisocyanates with polyols is insufficient, and the foam tends to be soft and the strength tends to decrease. On the other hand, when the isocyanate index exceeds 120, the foam tends to be hard and the water absorption is lowered.

  The foaming agent is for foaming polyurethane into a polyurethane foam. As the foaming agent, water, acid amide, carbon dioxide, or the like is used. The blending amount of the foaming agent is preferably 1.0 to 5.0 parts by mass with respect to 100 parts by mass of the polyols in order to reduce the amount of the foaming agent from the usual amount and suppress the progress of the curing reaction. When the blending amount of the foaming agent is less than 1.0 part by mass, the foaming reaction becomes insufficient, and when it exceeds 5.0 parts by mass, the foaming reaction and the crosslinking reaction become excessive, and the foam tends to become hard.

In addition to this foaming agent, an auxiliary foaming agent can also be blended. The auxiliary foaming agent is an organic solvent that is non-reactive with polyols and polyisocyanates, and is used to reduce the hardness of the foam. Examples of the auxiliary foaming agent include methylene chloride (methylene chloride, CH ₂ Cl ₂ ), n-pentane, cyclohexane, and fluorocarbon compounds (trichlorofluoromethane, dichlorodifluoromethane, etc.).

  The catalyst is for accelerating the urethanization reaction between polyols and polyisocyanates. Such catalysts include N, N ′, N′-trimethylaminoethylpiperazine, triethylenediamine, dimethylethanolamine, tertiary amines such as N-ethylmorpholine, organometallic compounds such as tin octylate, acetates, alkali metal alcoholates Etc. are used.

  Next, polyethylene glycol or a derivative thereof is a component for imparting hydrophilicity to the polyurethane foam. When this component reacts with polyisocyanates, it is incompatible with the polyurethane part that becomes the skeleton of the polyurethane foam, especially the polyurethane part obtained from polyester polyol, and is oriented on the surface, and is hydrophilic to the polyurethane foam. It is thought that it gives. Specific examples thereof include polyethylene glycol (polyethylene oxide), and derivatives thereof such as polyoxyethylene alkyl ether (alkyl group having 11 to 50 carbon atoms, usually 12 to 18 carbon atoms, ethylene oxide addition mole number 3 to 40), etc. Is used. The number of hydroxyl groups (number of functional groups) may be 1 or 2 or more. The molecular weight is about 200 to 600.

  In addition, as a raw material of the polyurethane foam, a foam stabilizer such as a surfactant, a flame retardant such as a condensed phosphate ester, an antioxidant, a plasticizer, an ultraviolet absorber, a colorant, and the like can be added.

  A polyurethane foam is produced by reacting the polyurethane foam raw material to foam and cure, but the reaction at that time is complicated, and basically the following reaction is the main component. . That is, addition polymerization reaction (polyurethanation reaction) between polyols and polyisocyanates, foaming (foaming) reaction between polyisocyanates and water as a blowing agent, and crosslinking between these reaction products and polyisocyanates ( Curing) reaction. Here, the above polyols react with polyisocyanates to form a basic skeleton of polyurethane, and polyethylene glycol or a derivative thereof also has a hydroxyl group and reacts with polyisocyanates. Is a component that exhibits incompatibility, is oriented on the surface, and exhibits hydrophilicity.

  When producing a polyurethane foam, a one-shot method or a prepolymer method is employed. The one-shot method is a method in which polyols and polyisocyanates are directly reacted. The prepolymer method is a method in which a part of a polyol and a polyisocyanate are reacted in advance to obtain a prepolymer having an isocyanate group or a hydroxyl group at a terminal, and the polyol or the polyisocyanate is reacted therewith. The one-shot method is a preferable method because the manufacturing process is one step compared to the prepolymer method, and there are few restrictions on the manufacturing conditions, and the manufacturing cost can be reduced.

  As a polyurethane foam, a slab polyurethane foam is preferable. The slab polyurethane foam discharges the reaction raw material (reaction mixture) mixed and stirred by the one-shot method onto a belt conveyor, and while the belt conveyor moves, the reaction raw material naturally foams at room temperature and atmospheric pressure. Obtained by curing. Thereafter, it is cured (cured) in a drying furnace and cut into a predetermined shape. In addition, a polyurethane foam can be obtained by a molding method, an on-site spray molding method, or the like.

  The obtained polyurethane foam preferably has 40 to 100 cells / 25 mm as defined in JIS K6400. When the number of cells is less than 40 cells / 25 mm, capillary action hardly occurs when the polyurethane foam is compressed, and the water absorption is lowered. On the other hand, when the number of cells exceeds 100 cells / 25 mm, physical properties such as strength of the polyurethane foam deteriorate.

  The polyurethane foam molded body 12 is heated and pressed to form a pressed molded body 16, which is heated at a temperature of 180 to 220 ° C. for about 3 to 10 minutes. If the temperature of the hot press is less than 180 ° C., the compression effect is weak, and if it exceeds 220 ° C., physical properties such as the strength of the polyurethane foam deteriorate, which is not preferable. Under such conditions, heat pressing is performed, and the polyurethane foam molded body 12 is usually compressed 3 to 10 times.

  Now, when producing a polyurethane foam, it is carried out by reacting a polyol and a polyisocyanate in the presence of a catalyst and water as a foaming agent to cause foaming and curing. In this case, the polyurethane foam raw material is blended with 0.5 to 10 parts by mass of a compound imparting hydrophilicity such as polyethylene glycol per 100 parts by mass of polyols. Thereby, while having the cell 11 of an open cell structure, the molded object 12 of the polyurethane foam to which hydrophilicity was provided is obtained. The molded body 12 is compressed 3 to 10 times by hot press molding. The compressed press-formed body 16 has a high-density coating 14 formed on both surfaces thereof, and a low-density foam layer is formed on the intermediate portion 15 thereof.

  When this press-molded body 16 is used as the polishing buff material 19, it is formed in a disk shape and both surfaces thereof are supported by the holding jig 21. Then, as shown in FIGS. 2A and 2B, the polishing buff material 19 is rotated, and the bulging portion 20 of the polishing buff material 19 is in a state where the polishing slurry 23 is discharged from the discharge portion 22. By contacting the notch portion 18 of the silicon wafer 17, the flash of the notch portion 18 is removed and polished to a mirror surface. At this time, in the intermediate portion 15 of the press-formed body 16 constituting the polishing buff material 19, the communication between the cells 11 is enhanced, so that the water in the polishing slurry 23 is easily absorbed into the cells 11 by capillary action. Further, polishing is performed efficiently while being released. On the other hand, since the coating 14 of the press-molded body 16 is non-water-absorbing, it is possible to prevent water from escaping from both surfaces of the polishing buff material 19, and to absorb and release water to the notch portion 18 of the silicon wafer 17. It can be limited to the protruding portion 20, and the polishing efficiency can be increased.

The effects exhibited by the above embodiment will be described collectively below.
In the manufacturing method of the polishing buff material 19 of the present embodiment, the molded body 12 obtained by reacting, foaming and curing the raw material of the polyurethane foam containing polyethylene glycol or a derivative thereof is heated and pressed, and the press surface The film 14 is formed on the film 13. Since the raw material of the polyurethane foam contains polyethylene glycol or a derivative thereof, hydrophilicity is imparted to the molded body 12 and water is added to the cells 11 of the press molded body 16 obtained by heating and pressing the molded body 12. Is fully absorbed.

  By using such a press-formed body 16 as the polishing buff material 19, water in the polishing slurry 23 is absorbed or released into the press-formed body 16, and sufficient polishing can be performed on the object to be polished. . Furthermore, since the coating 14 is formed on the press surface 13 of the press-molded body 16 and the coating 14 is non-water-absorbing, water absorption and water discharge are limited to a portion facing the object to be polished during polishing. Polishing can be performed efficiently.

  In addition, by blending 0.5 to 10 parts by mass of polyethylene glycol or its derivative with 100 parts by mass of polyol in the polyurethane foam raw material, hydrophilicity can be sufficiently imparted to the polyurethane foam and water absorption can be increased. Polishing can be performed satisfactorily.

  -Furthermore, the water absorption of a polyurethane foam can be improved by setting the cell number prescribed | regulated to JISK6400 of a polyurethane foam to the range of 40-100 piece / 25mm.

  In addition, by setting the compression ratio by the heating press in the range of 5 to 10 times, it is possible to improve the water absorption of the intermediate portion 15 and the non-water absorption of the coating 14 in the press-formed body 16.

Hereinafter, the embodiment will be described more specifically with reference to examples and comparative examples.
(Examples 1-5 and Comparative Example 1)
Polyurethane foam by reacting polyester polyol as the polyols shown in Table 1 and tolylene diisocyanate as the polyisocyanate, N-ethylmorpholine as the amine catalyst, and water in the presence of water as the foaming agent, followed by foaming and curing. Manufactured. The compounding amounts shown in Table 1 are all parts by mass. The obtained polyurethane foam (molded body 12) was compressed 3 times, 5 times, and 10 times under the conditions of 200 ° C. and 5 minutes by a heating press apparatus to obtain a compressed sample (press molded body 16). . The meanings of the abbreviations in Table 1 are as follows.

N2200: Polyester polyol, hydroxyl value 60 mgKOH / g, manufactured by Nippon Polyurethane Industry Co., Ltd. SE232: Silicone surfactant, manufactured by Nihon Unicar Co., Ltd. PEG200: Polyethylene glycol, molecular weight 200, hydroxyl value 561 mgKOH / g, functional group (hydroxyl group) Number 2
LS106P: polyoxyethylene alkyl ether, hydroxyl value 106 mgKOH / g, functional group (hydroxyl group) number 1, manufactured by Kao Corporation T-80: tolylene diisocyanate (80% by mass of 2,4-tolylene diisocyanate and 2,6- A mixture of 20% by weight of tolylene diisocyanate), manufactured by Nippon Polyurethane Industry Co., Ltd. For the obtained polyurethane foam, the density, the number of cells and the water absorption were measured by the methods shown below, and the results are also shown in Table 1. Described.

Density (kg / m ³ ) and number of cells (cells / 25 mm): Both were measured according to JIS K6400.
Water absorption: After applying 0.05 ml of water droplets to the surface of the polyurethane foam, the time (seconds) until the foam was completely absorbed from the surface of the foam was measured. This water absorption was performed on the surface of the foam (film 14) and its intermediate part 15.

表１に示した結果から、実施例１のポリウレタン発泡体においては、親水性を付与する化合物としてポリエチレングリコールを用いて製造され、得られた発泡体の圧縮によりその表面に皮膜１４が形成されている（５倍圧縮及び１０倍圧縮）。このため、中間部１５では連続気泡構造を形成するセル１１内への吸水性が向上し、しかも皮膜１４と中間部１５との間に吸水性の差を設けることができた。従って、そのプレス成形体１６を研磨用バフ材１９として使用できることが明らかとなった。実施例２においても、親水性を付与する化合物としてポリオキシエチレンアルキルエーテルを用いることにより、実施例１と同様の結果を得ることができた。

From the results shown in Table 1, the polyurethane foam of Example 1 was produced using polyethylene glycol as a compound imparting hydrophilicity, and a film 14 was formed on the surface by compression of the obtained foam. (5 times compression and 10 times compression). For this reason, the water absorption into the cell 11 forming the open cell structure was improved in the intermediate portion 15, and a difference in water absorption could be provided between the coating 14 and the intermediate portion 15. Therefore, it became clear that the press-molded body 16 can be used as the polishing buff material 19. Also in Example 2, the same results as in Example 1 could be obtained by using polyoxyethylene alkyl ether as the compound imparting hydrophilicity.

  In Example 3, since the blending amount of polyethylene glycol was increased, the hydrophilicity of the foam was increased, the water absorption at the intermediate part was improved even when the compression ratio was three times, and the gap between the film 14 and the intermediate part 15 was increased. A difference in water absorption could be provided. Also in Example 4, since the blending amount of the polyoxyethylene alkyl ether was increased, the hydrophilicity of the foam was increased, the water absorption was improved even when the compression ratio was 3 times, and between the coating 14 and the intermediate portion 15. A difference in water absorption could be provided. In Example 5, the blending amount of water as the foaming agent was decreased and the density of the foam was increased, but the same results as in Example 3 and Example 4 were obtained (however, at a compression ratio of 3 times) The water absorption was improved from that in Example 3 and Example 4).

On the other hand, in Comparative Example 1, since the polyurethane foam did not have hydrophilicity, no water absorption was observed even when compressed 3 to 10 times.
In addition, this embodiment can also be changed and embodied as follows.

  -As a derivative of polyethylene glycol, polyoxyethylene alkylphenyl ether such as polyethylene glycol monononylphenyl ether can be used.

The cross-sectional shape of the bulging portion 20 of the polishing buff material 19 can be changed to a triangular shape, a trapezoidal shape, or the like.
A surfactant having a hydrophilic / lipophilic ratio (HLB) of 8 to 18 may be blended as a raw material for the polyurethane foam to increase the hydrophilicity of the polyurethane foam.

A magnetic disk, a magneto-optical disk, or the like can be used as an object to be polished .

(A) is explanatory drawing which fractures | ruptures and shows the molded object of the polyurethane foam in embodiment, (b) is explanatory drawing which fractures | ruptures and shows the press-molding body obtained by heat-pressing. FIG. 4A is a plan view showing a state in which a silicon wafer is being polished with a polishing buff material, and FIG. 4B is a cross-sectional view showing a state in which the silicon wafer is being polished with a polishing buff material.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Molded object, 13 ... Press surface, 14 ... Film | membrane, 16 ... Press molded object, 19 ... Polishing buff material.

Claims (4)

A polyurethane foam obtained by reacting, foaming and curing a polyurethane foam material containing a polyol, a polyisocyanate, a foaming agent, a catalyst and polyethylene glycol or a derivative thereof comprising polyester polyol is heated and pressed. A method for producing a polishing buff material, comprising forming a film on the surface. 2. The method for producing a polishing buff material according to claim 1, wherein the blending amount of the polyethylene glycol or a derivative thereof is 0.5 to 10 parts by mass per 100 parts by mass of polyols. 3. The method for producing a polishing buff material according to claim 1, wherein the polyurethane foam has a number of cells defined in JIS K6400 of 40 to 100 cells / 25 mm. The method for producing a polishing buff material according to any one of claims 1 to 3, wherein a compression ratio by the heating press is 5 to 10 times.

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